The present invention, in general, relates to trench-digging implements, and more particularly to a machine for digging a trench under or adjacent to an existing structure that is not readily accessible.
Most permanent building structures require a solid foundation between the structure and the earth to support the weight of the structure. The foundation distributes and supports the load of the building and prevents the building from settling unevenly or sinking. Foundations are typically created by digging trenches around the future perimeter of a building structure. These trenches are then filled with concrete, which may be reinforced with steel, to create footings. The building is then built on these footings, with the footings supporting the load bearing walls and outer exterior of the building.
Formation of the footings for a building structure can be a large expenditure. Specifically, most structures require fairly wide and deep footings for support of the buildings. Digging the trenches manually with a shovel to form these footings can be labor intensive and a slow process.
To remedy these problems, power-driven machinery has been developed to replace manual labor for digging trenches. For example, one type of trench-digging machinery has been developed to dig or cut a trench in the ground using a chain saw configuration. These trench-digging machines typically include a digging implement containing a boom that supports a large chain containing teeth similar to a chain saw. When the chain is rotated, the teeth connected to the chain dig into the earth, thereby creating a trench. The digging implement is typically connected to a transport machine that supports and moves the digging implement into place for digging. The transport machine also typically includes a power source, such as a power take off shaft (PTO), chain and sprocket arrangement, or hydraulic pump and motor system, that causes the chain to rotate, thereby digging the trench.
An important limitation of many conventional trench-digging machines, however, is that they are typically not designed to dig under existing structures or to dig trenches in locations adjacent to an existing structure. Specifically, many trench-digging machines are configured such that the digging implement is connected to the rear of the transport vehicle in a position either at or near the centerline of the transport vehicle. As such, for the trench-digging machine to dig a trench, the transport vehicle must strattle the position where the trench is to be dug. If the trench is to be dug under an existing structure, however, the height of the transport vehicle may not provide proper clearance under the existing structure to properly position the digging implement for digging the trench. Similarly, if the trench is to be dug adjacent to an existing structure, the width of the transport vehicle may also prohibit placement of the digging implement adjacent to the existing structure.
An improved trench-digging machine is provided in accordance with the various embodiments of the present invention. According to one aspect of the present invention, a trench-digging machine is provided in which the digging implement is capable of being laterally offset beyond the lateral bounds of the transport machine, thereby enabling the trench-digging machine to dig trenches that are laterally displaced from the transport machine and are not merely located immediately behind the transport machine. According to another aspect of the present invention, an attachment plate and frame are provided that permit the digging implement of the trench-digging machine to be operably connected to the transport machine at a position closer to the ground, thereby reducing the clearance required for access by the digging implement. As such, the trench-digging machine of the present invention is capable of digging trenches in locations that were difficult, if not impossible, for conventional trench-digging machines to access. In this regard, the trench-digging machine of the present invention is advantageously adapted to dig trenches under existing structures.
The trench-digging machine includes a frame operably connected to a transport machine and a digging implement connected to the frame for digging a trench. As a frame of reference, the transport machine generally defines a lengthwise extending axis. In addition, the transport machine typically extends widthwise between a pair of lateral bounding planes that define the lateral extent of the transport machine. According to one advantageous embodiment, the frame is connected to the transport machine such that a center line of the digging implement is capable of being laterally offset from the lengthwise extending axis defined by the transport machine to a position beyond the respective lateral bounding plane of the transport machine. As such, the digging implement may be placed under an existing structure, even though the transport machine cannot similarly be positioned under the structure. Thus, the trench-digging machine of this embodiment is capable of digging trenches in locations otherwise inaccessible to a conventional trench-digging machine that extends immediately rearward of a transport machine.
In addition to the frame and the digging implement, the trench-digging machine of another embodiment includes an attachment plate for operable connection to the transport machine. Thus, the frame may be connected to the attachment plate in order to be operably connected to the transport machine. Relative to a vertical axis defined by the transport machine, the attachment plate of this embodiment is oriented at an angle xcex1 offset from vertical such that the attachment plate faces downwardly. In order to mate with the attachment plate, the frame may be configured to extend between a first face that is connected to the attachment plate and oriented at the same angle offset xcex1 from vertical as the attachment plate and an opposed second face having a vertical orientation. Thus, the digging implement may be connected to the second face of the frame so as to be connected to a surface having the desired vertical orientation. However, by operably connecting the frame to the transport machine by mean of an attachment plate that faces downwardly, the digging implement is connected to the frame at a position closer to the ground. As a result, the trench-digging machine of this embodiment requires less clearance so as to effectively reduce the distance by which a structure must be raised above the ground in order to permit the trench to be dug thereunder.
In one embodiment, the first face of the frame includes a pair of widthwise extending rails and at least one strut extending between the pair of rails to provide strength and rigidity. The attachment plate may therefore be connected to the at least one strut. As a result, the at least one strut of the frame also preferably extends to the same angle offset xcex1 from vertical as the attachment plate. By extending at an angle from vertical, the strut is generally somewhat longer than conventional vertical struts, thereby advantageously increasing the strength of the frame.
The attachment plate may be capable of connecting the frame to the transport machine at a plurality of positions, typically a plurality of positions laterally offset by different distances from the lengthwise extending axis defined by the transport machine. According to this embodiment, the center line of the digging implement carried by the frame is therefore adjustable with respect to the lengthwise extending axis of the transport machine by connecting the frame to the transport machine at different predetermined positions. Thus, the digging implement may be extended laterally beyond the transport machine during digging operations under a structure. However, the digging implement may be repositioned so as to extend rearward behind the transport machine, either for digging operations or for transportation of the transport machine.